Mobile communication systems using the W-CDMA system employ a configuration in which a transmission power of each channel other than PCPICH (Primary Common Pilot Channel) is set by using a value relative to a transmission power of PCPICH.
Here, a dedicated channel is configured to have an upper limit of the transmission power (hereinafter, “upper-limit transmission power”) and a lower limit of the transmission power (hereinafter, “lower-limit transmission power”) each set by using a value relative to the transmission power of PCPICH, and to transmit a dedicated channel with a transmission power within a range between the upper-limit transmission power and the lower-limit transmission power.
In such a mobile communication system, as shown in no. 5, when the transmission power of PCPICH is “X (dBm)”, and offset values of the upper-limit transmission power and the lower-limit transmission power are “−a (dB)” and “−b (dB)”, respectively, and an offset value of a transmission power of a certain common channel is “−c (dB)”, for example, the upper-limit transmission power of the dedicated channel is “X−a (dBm)”, the lower-limit transmission power of the dedicated channel is “X−b (dBm)”, and the transmission power of the common channel is “X−c (dBm)”.
Accordingly, when the transmission power of PCPICH is changed from “X (dBm)” to “Y (dBm)”, the upper-limit transmission power of the dedicated channel, the lower-limit transmission power of the dedicated channel and the transmission power of the common channel are automatically changed from “X−a (dBm)”, “X−b (dBm)” and “X−c (dBm)” to “Y−a (dBm)”, “Y−b (dBm)” and “Y−c (dBm)”, respectively.